Method of making sulphur trioxide and catalyst for use in said method



Patented June .14, 1932 UNITED STATES PATENT OFFICE NAPOLEON ARTHUR LAURY, OF ROGKVILLE CENTER, NEW YORK, ASSIGNOR, BY.MESNE ASSIGNMENTS, TO THE DELAWARE METHOD OF MAKING SULPHUR TRIOXIDE AND CATALYST FOR USE IN SAID METHOD No Drawing. a

This invention relates to a method of mak-. ing sulphur trioxide and to a catalyst for use in said method.

In making sulphuric acid by the contact method, it is customary to bring sulphur d1- oxide gas and oxygen into contact with a catalyst at a temperature of about 500 C. The most common catalyst for this purpose is platinum. Vanadium catalysts have been proposed, but have not, so far as I am aware, proved sufficiently successful to be adopted 1n commercial use generally. I have ascertained that the eficiency of a vanadium catalyst in oxidizing S0 to S0 is in a large degree dependent upon the nature of the carrier used for the catalyst. Various carriers have been proposed including diat0- maceous earth in powdered form. I have ascertained that a powdered carrier for the catalyzer involves a waste of the catalytic material by coating surfaces of the carrier with which gases cannot come in contact. Attempts'have been made to aggregate diatomaceous material after catalytic material has been applied to it, but the particles thus produced are easily friable, and, for that reason, difficult to handle and not infrequently injured in use.

I have discovered that a desirable catalytic mass can be made by applying the catalyst to a carrierconsisting of a natural aggregate of diatomaceous earth which has been fired to a temperature of 1000 C. in order to make its particles strong and non-friable. The particles of such a mass are massive, that is, the mass is not in powdered form, and have great physical strength which facilitates handlin the mass and prevents it from cracking and. ecoming pulverized in use. The great 40 physical strength given to the particles by heating to a temperatureof about 1000 C.

is believed to be the result of the fusion of a minute proportion of non-silicious' material occurring as an impurity in diatomaceous earth and fusible at a temperature below that at which the silicious'material itself would be fused or sintered. This fused material appears to act as a strong binder, although it is' present in such a minute quantity and is fusi- Me at such a temperature that neither its CALGO GHEMIGAL COMPANY, INC., A CORPORATION OF Application filed August 15, 1928. Serial No. 299,879.

fusion nor heating sufliciently to fuse it damages the lace-like surface of the particles which remains substantially as in natural diatomaceous particles. Because of the great physical strength thus given to the particles,

the mass remains easily permeable by the ticles great physical strength and render them non-friable. The mass is then spread out thin and sprayed with a solution of sodium vanadate (Nag, V0 or other soluble vanadium salt. For each pound of the aggregate, 0.4: pound of sodium vanadate is-used. After the mass has been thoroughly sprayed, it is dried, and is heated to a temperature of approximately 500 C. for one hour, preferably in an atmosphere of S0 The resulting mass is easily handled, and is an efficient catalytic mass for use in the contact method of making sul huric acid.

11 making sulphur trioxide by means of the catalytic mass above described, a mixture containing sulphur dioxide and oxygen is passed through the mass at an elevated temperature. As the vanadium is not injuriously aifected by arsenic and other impurities which poison a platinum catalyzer, the usual step of purifying the sulphur dioxide may be omitted.

What I claim is:

1. A catalytic mass for use in the contact method of making sulphuric acid, comprising massive particles of diatomaceous earth which are of a size sufiicient to make a mass of them easily gas-permeable and which have been heated to a temperature of approximately 1000 C. to render them non-friable, and a compound containing vanadium coated on said particles.

ture of 1000 C. to give the individual par- 2. The method of making a catalytic mass, which comprises heating massive particles of diatomaceous earth too large to pass through a U. S. standard six-mesh sieve to a 5 temperature of 1000 C. to render them nonfriable, spraying a solution of a vanadium salt on the surfaces of said particles, and then heating the particles to a temperature of approximately 500 in an atmosphere of sulphur dioxide.

3. The method of maln'ng a catalytic mass, which comprises firing massive particles of diatomaceous earth too large to pass through a U. S. standard six-mesh sieve to render them non-friable, applying a solution of a vanadium compound to said particles,'and then heating the particles in an atmosphere containing sulphur dioxide.

4. A catalytic mass for use in the contact method of making sulphuric acid, comprising natural diatomaceous particles which are ofsufiicient size to render the mass easily gas permeable and which have been fired to a temperature which renders them noncrumbling without changing their lace-like surface, and a catalytic material coated upon the surfaces of said particles.

5. The method of making a cat ytic'mass, which consists in firing natural diatomaeeoiis particles of a size sufficient to make a 111 ss of themeasily gas permeable and a 1 ng a coating of a eompound of vanadium to the fired particles; V 4

r The method mating l hur aide,

- which consists in passing a mixture o:-

ygcn and sulphur dioxide at an elevated tem- V perature through a gas-permeable massiof massive diatomaceous particles wiich have been rendered non cru mhling by firing and 0 have lace-like surfaces coated with a catalytic material. V

Inte'stimony whereof I have hereunto set my hand. p

NAPOLEON ARTHUR,LAURY. 

